Achroite

Big Photo

Afghanistan
10.91 carats
© irocks.com

Achroite (Greek - without colour) is colourless or almost colourless variety of Tourmaline. It is quite rare.

Achroite Gemstones by Colour

This table shows the variety of hues this gemstone can be found in. Click on a photo for more information.
 

Achroite Gemstones by Size

This table shows distribution of Achroite gemstone sizes that are listed on this site. This can give a good indication as to the general availability of this gemstone in different sizes.
Contributed photos
Lightest:4.86 cts
Heaviest:10.91 cts
Average:7.88 cts
Total photos:2
Do you have a larger Achroite? Why not upload a photo?
4.86ct to 5.47ct5.47ct to 6.07ct6.07ct to 6.68ct6.68ct to 7.28ct7.28ct to 7.89ct7.89ct to 8.49ct8.49ct to 9.10ct9.10ct to 9.70ct9.70ct to 10.31ct10.31ct to 10.91ct
General Information
A variety or type of:Tourmaline
Chemical Formula
Na(Li
 
1.5
Al
 
1.5
)Al
 
6
(Si
 
6
O
 
18
)(BO
 
3
)
 
3
(OH)
 
3
(OH)
Gemdat.org, Management Team (2012) Formula given for elbaite. Most, but not all, achroite is elbaite.More from other references
Photos of natural/un-cut material from mindat.org
Physical Properties of Achroite
Mohs Hardness7 to 7.5
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Specific Gravity2.90 to 3.40
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
TenacityBrittle
Walter Schumann, Gemstones of the world (2001)
Cleavage QualityIndistinct
Walter Schumann, Gemstones of the world (2001)
FractureUneven,Conchoidal
Walter Schumann, Gemstones of the world (2001)
Optical Properties of Achroite
Refractive Index1.614 to 1.666
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Optical CharacterUniaxial/-
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Birefringence0.014 to 0.040
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
Dispersion0.017
Walter Schumann, Gemstones of the world (2001)
Colour
Colour (General)Colorless
Herve Nicolas Lazzarelli, Blue Chart Gem Identification (2010)
TransparencyTransparent,Translucent,Opaque
Ulrich Henn and Claudio C. Milisenda, Gemmological Tables (2004)
LustreVitreous
gemdat.org, Editorial Team (2012)
Fluorescence & other light emissions
Fluorescence (General)Weak to none
Walter Schumann, Gemstones of the world (2001)
Crystallography of Achroite
Crystal SystemTrigonal
gemdat.org, Editorial Team (2012)
HabitLong crystals with triangular cross section and rounded sides, definite striation parallel to main axis
Walter Schumann, Gemstones of the world (2001)
Further Information
Mineral information:Achroite information at mindat.org
Significant Gem Localities
Afghanistan
 
Bowersox and Chamberlin (1995)
Sri Lanka
 
  • Sabaragamuwa Province
    • Ratnapura District
      • Ratnapura
USA
 
  • California
    • San Diego Co.
      • Warner Springs District
        • Warner Springs
Laurs (2001, 2002, 2004)
  • Maine
    • Oxford Co.
      • Newry
Freeman (2005)
      • Paris
Freeman (2005)
Copyright © Jolyon & Katya Ralph 1993-2019. Site Map. Locality, gem & photograph data are the copyright of the individuals who submitted them. For more information please contact the . Gemdat.org is an online information resource dedicated to providing free gemmological information to all.